What's the purpose of the preface to The Scarlet Letter?

The preface to The Scarlet Letter sets the atmosphere of the story and connects the present with the past. Hawthorne's description of the Salem port of the 1800s is directly related to the past history of the area. The Puritans who first settled in Massachusetts in the 1600s founded a colony that concentrated on God's teachings and their mission to live by His word. But this philosophy was eventually swallowed up by the commercialism and financial interests of the 1700s.

In this preface, Hawthorne also shares his definition of the romance novel as he attempts to imagine Hester Prynne's story beyond Pue's manuscript account. A careful reading of this section explains the author's use of light (chiaroscuro) and setting as romance techniques in developing his themes. Hawthorne explains that, in a certain light and time and place, objects "... seem to lose their actual substance, and become things of intellect." He asserts that, at the right time with the right scene before him, the romance writer can "dream strange things and make them look like truth."

Finally, the preface serves as means of authenticating the novel by explaining that Hawthorne had discovered in the Salem Custom House the faded scarlet A and the parchment sheets that contained the historical manuscript on which the novel is based. However, no serious, scholarly work suggests Hawthorne was ever actually in possession of the letter or the manuscript. This technique, typical of the narrative conventions of his time, serves as a way of giving his story an air of historic truth.